It would be nice to get some income from designs that we post that others decide to also get printed.
This has to be balanced against trying to keep the costs as low as possible because 3D printing is still not very cheap.

I would like to propose two possible mechanisms. Maybe others have more ideas too...?

1. Fixed amount per print. If another user prints one of my designs then I get a dollar (?).Advantages:
- Its simple and all parties can see the true costs.
- Its easy to manage on Shapeways end.
- If your design is successful and 50 prints are made then you get 50 USD.
- Your account could accumulate this money which you could choose to get when it exceeds (say) 20 dollars and/or use it to buy prints yourself.

Disadvantages:
- For designs that are only printed a small number of times - You may not make very much. So the cost of your effort to make the design is not well rewarded.

Summary:
This approach favors simplicity. Good designs will make a small amount of income. It does not reward users who design purely for the hope of sales.

2. User sets price. So profit is price - cost. Advantages:
- Designer sets the value of a piece
- More reward for designs that are designed to be "commercial".

Disadvantages:
- Designer may make a design people want to buy but price is too high.
And so may need to add feedback mechanisms, advertising, specials, etc - which turn Shapeways into more of a commerce site.
- Requires more work on website.

Summary:
More complex. Good designs wil make more money for the designer even if the number printed is low. (Conversely Shapeways may not make as much.) Shapeways needs to do more to beef up the sales aspect of the website.

I'm not sure where to vote here. The truth is, I would like to see more than a dollar for my designs, but not significantly more.

I'm guessing that shapeways is not at the moment focussing on commerce as much as it is focussing on prototypes and one offs for the artist.

You're right in saying that 3D printing is not cheap at the moment. And in truth, there are better materials out there to make most of these products (although it is close!).

Anyone's best bet is to use shapeways as an affordable way to make a prototype or a very small run (5 or less) of an item. Then prototypes should be taken into the casting process. Which brings up another interesting focus ...

Perhaps shapeways should get itself connected with a plastic foundry. And then the customer, after an initial print is made and delivered, could decide to opt into a production package with Shapeways' affiliate foundry.